In recent years, in association with an increase of use of digital works, a pirated edition of a disc by an illegal copy has become a large problem. Therefore, various copyright protecting systems to prevent the illegal copy have been proposed. For example, in a super audio CD, the following copyright protecting system has been proposed.
That is, on the disc manufacturing side, data encrypted by key information (hereinafter, referred to as a disc key) is recorded onto an optical disc and the disc key used for the encryption is embedded in the optical disc. On the disc reproducing apparatus side, the disc key embedded in the optical disc is detected and the data reproduced from the optical disc is decrypted by using the detected disc key.
FIG. 1 shows a construction of a conventional disc reproducing apparatus. As shown in FIG. 1, the disc reproducing apparatus is constructed by an RF processor 201, a data demodulating unit 202, a disc key detecting unit 203, a data decrypting unit 204, a data processing unit 205, a D/A unit 206, and a system controller 207.
The RF (Radio Frequency) processor 201 executes a process such as gain control or the like to a signal read out from an optical disc by an optical pickup (not shown) and supplies it to the data demodulating unit 202 and the disc key detecting unit 203.
The data demodulating unit 202 demodulates data supplied from the RF processor 201 and supplies it to the data decrypting unit 204.
On the basis of the data supplied from the RF processor 1, the disc key detecting unit 203 detects a disc key embedded in the optical disc. When the disc key is detected, the disc key is supplied to the data decrypting unit 204.
On the basis of the disc key supplied from the disc key detecting unit 203, the data decrypting unit 204 decrypts the data supplied from the data demodulating unit 202 and supplies it to the data processing unit 205.
When data of an audio block portion is supplied from the data decrypting unit 204, the data processing unit 205 divides each sector constructing the audio block portion into a header portion and a packet portion, supplies the header portion to the system controller 207, and supplies the packet portion to the D/A unit 206. When data of a TOC (Table of Contents) portion is supplied from the data decrypting unit 204, the data processing unit 205 supplies the data of the TOC portion to the system controller 207.
The D/A unit 206 D/A converts audio data which is supplied from the data processing unit 5 and outputs it to an external apparatus or the like.
On the basis of the data in the header portion and the TOC portion supplied from the data processing unit 205, the system controller 207 displays a music number, playing time, and the like.
FIG. 2 is a flowchart for explaining a reproducing process of the conventional disc reproducing apparatus. First, in step 101, on the basis of the data supplied from the optical pickup (not shown) to the disc key detecting unit 203, the disc key detecting unit 203 detects the disc key of the optical disc loaded into the disc reproducing apparatus via the RF processor 201.
If the disc key can be detected in step 101, on the basis of the disc key detected by the disc key detecting unit 3, the data decrypting unit 204 decrypts the data which is supplied from the data demodulating unit 202 and supplies it to the data processing unit 205 in step 102.
On the other hand, if the disc key cannot be detected in step 101, an error message to notify the user of the fact that the optical disc loaded in the disc reproducing apparatus is not a legal disc is displayed in step 103.
In the conventional disc reproducing apparatus, however, whether the detected disc key coincides with the disc key used for encryption of the data or not is not confirmed. Therefore, in the conventional disc reproducing apparatus, if the recording data is decrypted in the data decrypting unit 204 by a key different from the disc key used for the encryption of the data, the time which is displayed by a display is invalid and an audio output to the external apparatus becomes an unsatisfactory noise output.
Also in the case where the disc key detecting unit 203 has erroneously discriminated the presence or absence of the disc key and the data decrypting unit 204 has decrypted the data by the wrong key, the time which is displayed by the display is invalid and the audio output to the external apparatus becomes the unsatisfactory noise output.
Further, also in the case where the data decrypting unit 204 has erroneously executed the decrypting process of the data, the time which is displayed by the display is invalid and the audio output to the external apparatus becomes the unsatisfactory noise output.
It is, therefore, the first object of the invention to provide a reproducing apparatus, a reproducing method, and a disc reproducing apparatus, in which whether a detected disc key coincides with a disc key used for encryption of data or not is discriminated and if it is confirmed that the disc key is invalid, an external output of audio data can be suppressed.
It is the second object of the invention to provide a reproducing apparatus, a reproducing method, and a disc reproducing apparatus, in which if there is an error in discrimination about the presence or absence of a disc key, an external output of audio data can be suppressed.
It is the third object of the invention to provide a reproducing apparatus, a reproducing method, and a disc reproducing apparatus, in which if data is erroneously decrypted, an external output of audio data to an external apparatus can be suppressed.